【摘要】 利用PCR技术扩增青海湖3个不同地区(黑马河,布哈河,沙柳河)的青海湖裸鲤(Gymnocypris przewalskii(Kessler))线粒体D-loop基因片段,测定该基因片段1 005 bp序列。通过线粒体基因组D-loop区序列比较分析,对比3个不同地区的83尾青海湖裸鲤的遗传结构进行研究,共检测出多态性位点65个,其中有1个插入位点(b3,nt-569),2个缺失位点(s6和b37,nt-169、nt-170),多态性位点数62。3个群体内的多态性位点分别为黑马河51个、布哈河38个、沙柳河39个,平均核苷酸位点差异数分别为9.377、7.782和7.510。结果表明,不同地区的遗传距离分别为黑马河群体与布哈河群体间的平均遗传距离最小(0.010 93),布哈河群体与沙柳河群体次之(0.014 23),黑马河群体与沙柳河群体的遗传平均距离最大(0.019 09)。3个群体间的遗传平均距离都在0.01以上,而且3个群体间总的遗传分化指数为0.019 26,基因流为12.73。UPGMA法构建的分子系统树中,沙柳河群体聚成一支,黑马河和布哈河群体混杂在一起,聚成一支。从序列差异的分析中得出,沙柳河群体与黑马河和布哈河群体的亲缘关系较远;黑马河和布哈河群体亲缘关系较近。以上数据还表明,青海湖裸鲤3个繁殖群体间具有较弱的遗传分化,洄游到同一河流里进行交配繁殖的群体内基因交流作用比较大,而洄游到不同河流进行繁殖的群体间的基因交流相对较小更多还原

【Abstract】 The Qinghai Lake is the largest inland brackish water lake in China with a high salt and alkali contents,covering an area of 4?456?km² and being located 3?200 meters above sea level.It is located in the north-east of the Qinghai-Tibet Plateau,where the climate is cold and the freezing season is long.Gymnocypris przewalskii（Kessler） is a brackish and cold water fish species peculiar to the Qinghai Lake and its tributaries which has evolved in the long period of geographical isolation of the water system of the Yellow River having significant migration for reproduction.Every year,it ascends to the tributaries for spawning from March to July.It has low fecundity.It is omnivores,feeding on planktons and the insects fallen into the water.It is economically an very important fish species in the area of the Qinghai Lake.In recent decades,the deterioration of ecological environments（such as dryness of the inflowing rivers,sharp decline in precipitation,decease in water level,increase in evaporation and salt contents of the lake water etc.） and over-fishing in the Lake area have led to a decrease of their stock abundance by 90% in comparison with that at the beginning of its exploitation.Now,it has became an endangered fish and listed as the state-protected rare species.Judging from phenotypic characters,there exists a rather large variability within the species,which is reflected in the variabilities in their feeding organs,such as the number of gill-rakers,the position of mouth and the lengths of intestines.These are consistent with the character of omnivority that has been formed in their survival environment for the paucity of food organisms.Besides,there are considerable variabilities in body form and body color.In this study,PCR（polymerase chain reaction） technique was used in an attempt to analyze the genetic structure of this fish species at mitochondrial D-loop level,in order to provide a new base for the assessment and protection of its population genetic diversities.The materials used in this experiment were collected from the Heima River,the Buha River and the Shaliu River,in July,2002,when G.przewalskii ascended for reproduction,with a total of 45 specimens,ie 15 samples from per river.3-5?g of muscle tissue per individual was taken for preservation in anhydrous alcohol.The mitochondrial D-loop of Gymnocypris przewalskii（Kessler） from different districts（the Heimahe River、the Buhahe River and the Shaliuhe River） of the Qinghaihu Lake were amplified by using polymerase chain reaction（PCR） technique,its sequence being determined to be 1?065?bp.A research was conducted on the genetic structure of 83 individuals from the 3 districts through a comparative analysis of D-loop sequence of their mitochordria genome.A total of 65 polymorphic sites were detected,including an insertion site（b3,nt-569）,two deletions（s6 and b37,nt-169 and nt-170） and 62 polymorphic sites.The number of polymorphic sites are 51 for the Heimahe population（Hm）,38 for the Buhahe population（Bh） and 39 for the Shaliuhe population（Sl）,respectively,with the different number of average nucleotide sites of the three population being 9.377,7.782 and 7.510,respectively.The results showed that the genetic distance between Hm and Bh was the smallest（0.010?93）,between Bh and Sl secondly（0.014?23）,and between Hm and Sl the largest（0.019?09）.The genetic distance between any two populations was all above 0.10,and the total genetic differentiation index of the three population was 0.019?26.The gene flow Nm was 12.73.In the molecular phylogenetic tree constructed in the method of UPGMA,Sl aggregated a branch,and Hm and Bh were mixed together,aggregating into another branch.Judged by sequence difference analysis,Sl was more distantly related up Hm than to Bh,while Hm and Bh were more closely related.The above data also showed that there existed quite a weak genetic differentiation and quite a strong gene exchange among the three population simultaneously.更多还原